Because AB=DE=EB, ∠A=2a.

∠CDB=3a, because BC=BD, ∠C=3a.

Because AB=AC, ∠ABC=3a.

∠A+∠C+∠ABC=2a+3a+3a= 180

The solution is a = 22.5.

So ∠A=2a=22.5 times 2 = 45. . Okay？